The invention relates to improvements in apparatus for transporting rod-shaped articles of the tobacco processing industry, and more particularly to improvements in apparatus for manipulating receptacles in the form of so-called chargers or trays which are used to temporarily store and transport arrays of parallel filter rod sections or plain filter cigarettes, cigars, cigarillos and like rod-shaped articles containing tobacco or being used in conjunction with tobacco-containing products. The invention will be described with reference to apparatus for the manipulation of receptacles for plain or filter cigarettes, but the apparatus can be used with equal or similar advantage to manipulate receptacles for temporary storage of other rod-shaped articles of the tobacco processing industry.
Modern production lines for cigarettes employ mass flow conveyors for direct transport of large quantities of cigarettes from a maker (such as a cigarette making machine or a filter tipping machine) to a processing machine (such as a packing machine or a reservoir). It is necessary to equip such production lines with buffer systems for temporary storage of excessive output of the maker when the output of the maker exceeds the requirements of the processing machine, and for admission of stored articles to the processing machine when the requirements of the processing machine exceed the output of the maker. A presently known and highly satisfactory buffer system employs an apparatus (hereinafter called filling unit) which has means for storing cigarettes in receptacles in the form of chargers or trays (hereinafter trays) and facilitates for temporary storage of empty and filled trays, and an apparatus (hereinafter called evacuating unit) which has means for discharging cigarettes from filled trays into the conveyor between the maker and the processing machine as well as facilities for temporary storage of filled and empty trays.
U.S. Pat. No. 4,564,329 to Bantien discloses an apparatus wherein a two-storey turret is employed as a means for transferring trays between the tray filling and tray evacuating units as well as between such units and a mobile magazine. The turret has two tray holders at each of the two levels but is incapable of moving trays between the levels. This necessitates such design of the magazine, tray filling unit and tray evacuating unit that all empty trays are transported at one of the two levels and all filled trays are transported at the other level. This detracts from the versatility of the apparatus, especially since it is desirable to keep empty trays at the upper level in the tray filling unit but at the lower level in the tray evacuating unit.
U.S. Pat. No. 4,585,386 to Gomann et al discloses a modified apparatus which can transport a mass flow of cigarettes directly from a maker to a processing machine and wherein the surplus of articles is stored in trays. The tray filling unit of this apparatus is directly coupled with the tray evacuating unit. Cigarettes which are discharged from trays in the tray evacuating unit are advanced by a mass flow conveyor along an arc of 180.degree. to merge into the mass flow which is conveyed directly from the maker to the processing machine. In accordance with a modification, filled and empty trays are transported along a path which subtends an arc of 180.degree. and connects the tray filling unit with the tray evacuating unit. The apparatus of Gomann et al. does not employ a mobile magazine and/or any means for transferring trays between such magazine and the tray filling and/or evacuating unit.
German Offenlegungsschrift No. 1,757,432 discloses an apparatus wherein each tray filling unit and each tray evacuating unit is associated with a discrete transfer device which can transfer empty or filled trays between the respective unit and a conveyor serving to circulate the trays along an endless path. Each tray filling unit delivers all filled trays to the conveyor which circulates the filled trays until a tray evacuating unit reports the need for filled trays whose contents are to be delivered to a particular processing machine. Filled trays which are supplied by several tray filling units circulate with empty trays which are supplied by several tray evacuating units. A drawback of this proposal is that a tray filling unit is likely to receive empty trays with a certain delay following the generation of a signal that the output of a maker exceeds the requirements of the associated processing machine, and that a tray evacuating unit is likely to receive filled trays with a certain delay because the conveyor cannot always maintain a filled tray in immediate proximity of the tray filling unit which is associated with a conveyor for delivery of cigarettes to a processing machine whose requirements then exceed the output of the corresponding maker. A delay in removal of the surplus which is turned out by a maker or a delay in admission of stored articles to a processing machine which cannot be adequately supplied by the corresponding maker can affect the operation of the production line, e.g., by necessitating a complete shutdown of a maker or of a processing machine with attendant huge losses in output and the production of rejects during deceleration and acceleration of the maker or the processing machine.